The present invention relates to an apparatus and method for removing dross ridges from the sides edges and ends of metal workpieces, as slabs, blooms, billets, or the like.
In the production of steel by, for example, the continuous casting process, the continuous casting emerging from the caster is transversely cut into desired lengths and it may also be cut or slit longitudinally to form two or more workpieces of the same length. The resulting separate metal workpieces, which are commonly referred to as slabs or blooms, are then subjected to subsequent processing, as by rolling, to form a finished steel product.
The cutting operations as described above are conventionally performed by means of a flame or torch, wherein a jet of high purity oxygen is directed against the workpiece while it is heated to the oxygen ignition temperature. The resulting exothermic chemical reaction between the iron and oxygen produces slag or waste, which consists of iron oxide, metallic iron and other alloy elements. This slag or waste is in the molten state, and it is displaced during the cutting operation and a portion thereof forms a ridge of the material along the lower edge of the cut. Upon cooling, the material solidifies and adheres to the workpiece surface along the bottom surface adjacent the cut, and forms what is commonly called a "dross ridge".
The formation of the dross ridges on the workpiece presents problems in the further processing thereof. For example, a dross ridge may drop off in the reheat furnace, which requires that it then be removed, thus involving additional labor. Also, in the event the dross ridge remains adhered to the workpiece during reheating, it is laminated into the steel during rolling of the workpiece, resulting in an inferior product.
Heretofore, the dross ridges resulting from a torch cutting operation have been removed by a process involving inverting the workpiece and removing the dross ridges with scarfing torches. However, the required additional handling of the workpiece entails additional equipment and labor. Mechanical chippers or chisels have been employed for this purpose, but this also is a labor intensive process.
U.S. Pat. No. 2,301,923 suggests a process for dross removal which involves immediately cooling the slag as it emerges from the cut, and so that it rapidly solidifies and may be easily removed by a subsequent mechanical operation. This prior patent also states that it has been previously proposed to remove such slag formations from a hot workpiece by means of a shear, but it is indicated that this prior proposal was not entirely satisfactory since the shear was subject to slag accumulation due to its hot condition.
More recent U.S. Pat. No. 4,390,167 discloses the use of rotary metal cutters for removal of slag of the described type from an advancing workpiece, and this patent also discloses that the cutters may take the form of a plurality of tools arranged on a vertically movable mount. However, these cutters appear to be able to remove dross ridges only along one of the ends of the workpiece, and it is believed the cutters would be subject to jamming and would require substantial maintenance.
The copending application of the present inventor, Ser. No. 013,134,, filed February 10, 1987, and entitled Apparatus and Method for Removing Dross Ridges from a Metal Workpiece, discloses in apparatus and method for removing the dross ridges at the two opposite ends of a workpiece, and which avoids many of the limitations and disadvantages of the known prior art procedures. However, this prior invention has no provision for removing dross ridges along the longitudinal sides of the workpiece.
It is an object of the present invention to provide an apparatus and method for efficiently removing dross ridges formed on metal workpieces during a torch cutting operation or the like, which avoids the limitations and disadvantages of the known prior art procedures, and which also is adapted to remove dross ridges from the sides of the workpiece as well as the ends thereof.
It is also an object of the present invention to provide an apparatus for removing dross ridges without requiring the inverting or other complex manipulation of the workpiece.
It is also an object of the present invention to provide an apparatus of the described type and which is characterized by its simplicity of construction and reliability of operation.
It is still another object of the present invention to provide an apparatus of the described type and which is adapted to remove dross ridges from a workpiece which is either hot or cold.